Applying shingles to a roof has typically been manually performed by placing one shingle at a time to the roof and either stapling or nailing that shingle with a hammer or pneumatic gun. The process requires continuous bending typically resulting in concentrated stress in the back and knees of the roofer. Manual roofing is a tedious and substantially time-consuming operation. An unusual proportion of time is utilized in moving shingles to the work area, positioning each shingle before nailing, then moving the whole operation across the roof after the application of a series of shingles has removed the roofer from his source of shingles. Shingles are typically applied to the roof in rows, requiring the roofer to draw a line across the roof along which the top of each shingle in that row must be meticulously aligned. Obviously, manual application of shingles is a time-consuming and strenuous operation.
Numerous shingle applying apparatus have been utilized in an attempt to alleviate the rigors of manual roofing. Examples of such apparatus include the following: U.S. Pat. No. 3,972,462 issued to Evans et.al. teaches a frame supported by wheels for lateral movement across a roof. The frame supports a chute on which a shingle is placed to slide against a guidebar. The guidebar is aligned in relation to the upper edge of a row of shingles previously connected to the roof. The frame supports a plurality of nail guns which are selectively pivoted to engage the shingle currently positioned on the chute and fasten each shingle to the roof.
U.S. Pat. No. 4,656,808 issued to Mansfield teaches a drum mounted for rotation in a frame. Shingles are placed on the drum, being secured thereon by ridges connected to the drum specially fitted for engagement within rain-grooves typically defined on such shingles. As the drum is rolled forward, the shingle is conveyed thereon to contact the roof. The shingle is gravitationally disengaged from the drum and automatically nailed by a nail gun. The drum may be indexed up the slope of the roof by a pair of hydraulic pistons mounted on cross-shafts.
As shown in FIG. 5, Evans et.al. requires that the shingle be laterally forced across a chute thereby bending the shingle at its most inflexible point. Shingles are typically made of a semi-rigid combination of tar and granular material such as sand and gravel. Though the shingle could be easily bent along its length, substantial lateral bending will damage the shingle. Evans et.al. still requires the user to bend over on his knees during the entire shingle applying procedure. Each shingle must be laid one at a time with the machine being moved and reset between the placement of each shingle. Since the invention taught in Evans et.al. is designed to lay shingles guided by the upper edge of a previously laid row, the first row would have to be applied to the roof by hand. Evans et.al. teaches a machine which can only overlap the shingles by one predetermined distance. Also, each row of shingles must be laid parallel to the other rows even though fanning the rows of shingles across the roof is a necessary practice to accommodate uneven eaves and gables. It appears that the traditional problems with laying shingles have not been eliminated by the invention taught in Evans et.al.
The invention taught by Mansfield in U.S. Pat. No. 4,656,808 must be kept in alignment visually. The invention taught by Mansfield must also be stopped to load a shingle or in the alternative requires two operators for continuous motion. Though the invention taught in Mansfield may be indexed up the roof's slope, the index distance and consequently the overlap of the shingles applied by such invention are non-adjustable. As previously mentioned, shingles are secured to the drum by fitting the rain-grooves defined by the shingles over and around a plurality of ridges circumferentially spaced around the drum. However, there currently exists many styles of shingles that no longer utilize raingrooves and the invention taught by Mansfield would not be able to apply such shingles. Mansfield teaches of stapler means automatically triggered by the rotation of the drum. However, the stapler means are mounted on the frame and as the drum is propelled forward the stapler means are suspended a substantial distance above the roof. This distance varies since the frame is pivotally mounted to the drum being susceptible to a rocking motion as the drum is propelled. Consequently, as the staples are fired from the stapler means, their accuracy is affected by the rocking motion of the frame. By being suspended above the surface of the roof, the stapler means will not be able to consistently project staples into the shingle. Close proximity of the stapler means discharge portal with the shingle to be stapled is required to project the staple completely within the shingle and the underlying roof. If the staple does not completely extend within the shingle and the underlying roof, other shingles applied over such staples will be damaged by the protruding staple thereby resulting in leakage.